As a method for analyzing a substance having a phosphate group, for example a phosphorylated biological substance and the like, a method based on enzyme-linked immunosorbent assay (ELISA) or a method utilizing a radioisotope has been known.
The enzyme-linked immunosorbent assay utilizes a principle that an antibody (or an antigen as well) bonds specifically to a target substance. Hence, there is a problem that it is necessary to obtain and purify a large quantity of the intended substance for preparing specific antibody against the intended substance. Further, there is another problem that it requires a long time to prepare an antibody since immune response of an animal is used for the preparation thereof. In addition, there is a problem that an antibody against a phosphorylated site in a molecular structure of a few kDa (Dalton) or less cannot be prepared and therefore a phosphorylated biological substance having such a molecular structure cannot be analyzed by an enzyme-linked immunosorbent assay.
Furthermore, a method using a radioisotope employs a radioisotope, 32P. Consequently, there is a problem that it is accompanied by complicated operations of radiation control and waste water management in a laboratory.
As a method for reducing phosphoric acid concentration in waste water, a method wherein a complex metal hydroxide is used, is disclosed in Japanese Unexamined Patent Publication No. H11-57695. On the other hand in the field of pharmaceuticals, a polymer bonded to a guanidino group is disclosed in Japanese Unexamined Patent Publication No. H08-506846 in use for the medical treatment of hyperphosphatemia. However, a complex metal hydroxide and a polymer bonded to a guanidino group have weak bonding strength to a phosphate group. Hence, there is a problem that a large quantity of complex metal hydroxide or a polymer bonded to a guanidino group as a bonding substrate to a phosphate group has to be used in order to capture a predetermined quantity of phosphoric acid.
On the other hand, as a compound that strongly bonds to a phosphate group, a macrocyclic polyamine zinc complex is disclosed in Journal of the American Chemical Society (the United States of America), Vol. 113, NO. 23, p. 8935-8941, (1991). However, a macrocyclic polyamine zinc complex is soluble to a solvent. Hence, there is a problem that it is very difficult to separate and purify a substance having a phosphate group bonded to a macrocyclic polyamine zinc complex, in a solvent.
Accordingly, for the purpose of separating and purifying a substance having a phosphate group such as a phosphorylated biological substance and the like, a capturing agent has been sought after which has, under a certain condition, characteristics of strongly bonding to a phosphate group that is one of anionic substituents and of being easily separated and purified as well, and is also safe and inexpensive.
The objective of the present invention is to provide a capturing agent which bonds, under a certain condition, to an anionic substituent (a phosphate group, for example) and also makes it easy to separate and purify a substance having the said subsitituent and is safe and inexpensive, a simple and convenient capturing apparatus filled with the said capturing agent, and an easy and prompt capture method thereof.